Spring startup - no go

Ok just on my way to work so won't get your reply till I get home in the AM.

So since I couldn't get my Yardworks 16.5hp Briggs & Stratton riding mower going in the spring I have done this so far. Oh and it is 4-5 years old.

1. Replaced battery as the old one would not accept a charge.
2. Replaced spark plug as the old one had just a weak orange spark.

After the first 2 things the mower will turn over but won't start

3. Added a dab of gas into spark plug hole to try to get it to start.
4. Took the air breather off for the carb and added gas directly into the carb.

A few things others have told me was it could be the fuel solenoid not letting gas into the engine but that should have been bypassed by me adding gas directly into the carb.

I have seen others while searching on internet that it could be the flywheel key but have not had the time to check that yet. Also not really set up to take that off.

Could I be missing a safety somewhere? Also I have old gas in it and in the 4-5 years I have had it I have not changed the air filter. Oil is good was changed last year.

I think thats it. Any suggestions would be appreciated.

Thanks,
Drew